|United States Patent||5,391,329|
|Dougherty, et. al.||Feb. 21, 1995|
|Inventors:||Dougherty; Thomas K. (Playa Del Rey, CA); Elias; William E. (El Segundo, CA); Kost; Alan R. (Woodland Hills, CA); Klein; Marvin B. (Pacific Palisades, CA).|
|Assignee:||Hughes Aircraft Company (Los Angeles, CA).|
|Filed:||Aug. 23, 1993|
|Intl. Cl.:||B29D 11/00;|
|U.S. Cl.:||264/1.7; 156/228.;|
|Field of Search:||1.7;2.7;320;325;1.9;1.1;216 |
|4,360,483||Nov., 1982||Ayres||264/ 2 .7|
|4,659,407||Apr., 1987||Lacotte et al.||156/228|
|4,878,973||Nov., 1989||Ohtake et al.||264/ 1 .7|
|5,080,469||Jan., 1992||McCahon et al.||359/241|
|5,172,278||Dec., 1992||Tutt et al.||359/885|
Primary Examiner: Vargot; Mathieu D.
An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.
This invention was made with United States Government support under Contract No. N62269-90-C-0239 awarded by the Department of the Navy. The United States Government has certain rights in this invention.